From the Apollo 13 radio transcript, as they're going through the Lunar Module activation checklist:
060:58:58 Lousma: Okay. The only item on page 10 is to deploy the landing gear.
060:59:06 Lovell: Okay, we'll do that now.
061:00:10 Haise: Okay. The landing gear are down and locked, Jack, and looking ahead now at page 11, we've done all of that.
They're clearly not planning to land anywhere, and any balance disturbance from having the gear up is dwarfed by the balance issues of having the CSM hanging off the docking port, so why didn't they skip it? They skipped a number of other non-essential steps in the procedure (such as activating the S-band antenna), so why not this one?